1. Field of the Invention
The present invention relates to a circularly-curved piston engine, and more particularly to a circularly-curved piston engine provided with both a circularly-curved cylinder and a cylindrical piston fitting and reciprocating within the cylinder. The piston engine of the present invention is applicable to any other reciprocating engine or mechanism such as reciprocating internal combustion engines, reciprocating external combustion engines, reciprocating compressors and like machines.
2. Description of the Related Art
In a so-called reciprocating internal combustion engine typical of the piston engines, there is employed a slider-crank mechanism comprising: a cylinder; a cylindrical piston which linearly reciprocates within the cylinder; a connecting rod which has one of its opposite ends rotatably connected with the cylindrical piston and the other rotatably connected with a crank shaft. In this reciprocating engine, the linear reciprocating motion of the cylindrical piston is converted into rotary, or turning motion through the connecting rod.
In the above-mentioned conventional piston engine, when the piston moves up and down within the cylinder, the connecting rod is periodically tilted from a direction of up-and-down motion of the piston. Due to the presence of this periodic tilt of the connecting rod, the piston is subjected to periodic side pressures which cause the piston to hit and rub the cylinder, i.e., cause a so-called xe2x80x9cpiston slapxe2x80x9d forming a major factor in vibrations, noises and friction losses in the piston engine.
Further, unbalance mass or inertia in each of the pistons, piston pins, connecting rods and like reciprocating components of the piston engine causes the engine to vibrate and to issue noises.
In each of cylinders of a multiple-cylinder type reciprocating internal combustion engine, the complete cycle of events requires four piston strokes (i.e., combustion, exhaust, intake, and compression), which cause variation in output torque of the engine, torsional vibrations of the crank shaft and noises. Further, due to the presence of couples of forces in inertia or mass as to the individual engine components such as the cylindrical pistons, piston pins, connecting rods, and like moving components, the crank shaft further suffers from additional vibrations caused by the above couples of forces in inertia or mass and also suffers from additional noises caused thereby.
These disadvantages appearing in the reciprocating internal combustion engines appear also in the reciprocating external combustion engines, reciprocating compressors, and various types of actuators.
It is an object of the present invention to provide a circularly-curved piston engine, which is free from the above-mentioned disadvantages inherent in the conventional reciprocating piston engine, i.e., substantially free from any vibrations and noises, small in friction loss, improved in machine efficiency, and is compact and lightweight.
The above object of the present invention is accomplished by providing:
A circularly-curved piston engine comprising:
a plurality of circularly-curved cylinders each assuming a circular shape in cross section;
a plurality of circularly-curved cylindrical pistons each fitting and reciprocating within each of the cylinders;
a rotor carrying the pistons to keep them in balance and to have them be rockable about the center of the rotor along their orbits relative to the cylinders, wherein the rotor is provided with a pair of connecting rods to impart half a rocking power of the rotor to each of a pair of crank shafts each of which converts the half of the rocking power to a piece of torque on its axis of rotation;
a gear mechanism for receiving a pair of these pieces of torque to combine them into an output power; and
an output shaft connected with the gear mechanism for receiving and out-putting the output power.
In the piston engine of the present invention having the above construction, the circularly-curved cylindrical piston is free from any side pressure during its reciprocating or rocking motion. Consequently, the piston engine of the present invention is free from vibrations, noises, and friction losses caused by the piston slap.
Further, in the piston engine of the present invention, the rotor is provided with a pair of the balanced connecting rods to impart half the rotor""s rocking power to each of a pair of the balanced crank shafts each of which converts the half of the rocking power to a piece of torque on its axis of rotation. Consequently, the piston engine of the present invention is completely balanced in reciprocating mass or inertia, and, therefore free from any vibrations and noises caused by an unbalanced mass or inertia.
Further, in the case of the internal combustion engine according to the present invention, since any torque produced during the piston strokes (i.e., combustion, exhaust, intake, and compression) of the engine appears in the same plane, there is no fear that the rotor is subjected to a torsional stress. Further, in the piston engine of the present invention, power transmission from the pair of the connecting rods to the corresponding pair of the crank shafts is performed on the same plane, which prevents the individual crank shafts from being subjected to any harmful couples of forces.
Furthermore, in the engine of the present invention, since the crank shaft is downsized in its turning radius, the crank pin may overlap in cross section with the crank shaft in more area than before, which may strengthen the individual crank shafts in stiffness, and permit both the crank pins and the crank shafts to be reduced in diameter. Further, when the present invention is applied to a four-cylinder single-acting four-cycle reciprocating piston engine, the number of the connecting rods is reduced to two. Incidentally, the corresponding conventional four-cylinder single-acting four-cycle reciprocating piston engine requires four connecting rods. Such considerable reduction in the number of the connecting rods means that the engine of the present invention may reduce its friction loss to a considerable extent.
Preferably, in the piston engine of the present invention having the above construction, the gear mechanism comprises:
a pair of first spur gears each fixedly mounted on each of the crank shafts; and
a second spur gear fixedly mounted on the output shaft and meshed with both the first spur gears.
Further, preferably, the above gear mechanism comprises:
a pair of first bevel gears each fixedly mounted on each of the crank shafts; and
a second bevel gear fixedly mounted on the output shaft and meshed with both the first bevel gears.
Preferably, in the piston engine of the present invention having the above construction:
the rotor is provided with a dovetail groove;
the piston is provided with a rotor-mounted end portion assuming a wedge shape, and has the rotor-mounted end portion inserted in the dovetail groove of the rotor;
whereby the piston is fixedly mounted on the rotor.
Further, preferably: the rotor is provided with a dovetail groove; the piston is provided with a rotor-mounted end portion assuming a wedge shape, and has the rotor-mounted end portion inserted in the dovetail groove of the rotor, a pair of the pistons being diametrically opposed to each other with respect to the center of the rotor; the rotor-mounted end portion assuming the wedge shape of the piston is provided with a circularly-curved wall portion; and, a compression ring is disposed radially inwardly between the circularly-curved wall portions of the pair of the pistons to urge the wall portions radially outwardly.
Preferably, in the piston engine of the present invention:
the rotor is provided with a dovetail groove;
the piston is provided with a rotor-mounted end portion assuming a wedge shape, and has the rotor-mounted end portion inserted in the dovetail groove of the rotor, a pair of the pistons being diametrically opposed to each other with respect to the center of the rotor;
the rotor-mounted end portion assuming the wedge shape of the piston is provided with a circularly-curved wall portion;
a compression ring is disposed radially inwardly between the circularly-curved wall portions of the pair of the pistons to urge the wall portions radially outwardly; and
a plurality of piston rings are embedded in an outer surface of the piston so as to be oppositely disposed to an inner surface of the cylinder.
Further, preferably: the rotor is provided with a dovetail groove; the piston is provided with a rotor-mounted end portion assuming a wedge shape, and has the rotor-mounted end portion inserted in the dovetail groove of the rotor, a pair of the pistons being diametrically opposed to each other with respect to the center of the rotor; the rotor-mounted end portion assuming the wedge shape of the piston is provided with a circularly-curved wall portion; a compression ring is disposed radially inwardly between the circularly-curved wall portions of the pair of the pistons to urge the wall portions radially outwardly; a plurality of piston rings are embedded in an outer surface of the piston so as to be oppositely disposed to an inner surface of the cylinder; the rotor is provided with an upper and a lower flange portion in its upper and its lower surface, respectively, the flange portions being coaxially arranged with the circularly-curved wall porions of the pistons; and, each of an upper and a lower rotor ring is radially outwardly disposed to encircle each of the upper and the lower flange portion of the rotor and each of the circularly-curved wall portions of the pistons.
Still further, preferably, in the piston engine of the present invention:
the rotor is provided with a dovetail groove;
the piston is provided with a rotor-mounted end portion assuming a wedge shape, and has the rotor-mounted end portion inserted in the dovetail groove of the rotor, a pair of the pistons being diametrically opposed to each other with respect to the center of the rotor;
the rotor-mounted end portion assuming the wedge shape of the piston is provided with a circularly-curved wall portion;
a compression ring is disposed radially inwardly between the circularly-curved wall portions of the pair of the pistons to urge the wall portions radially outwardly;
a plurality of piston rings are embedded in an outer surface of the piston so as to be oppositely disposed to an inner surface of the cylinder;
the rotor is provided with an upper and a lower flange portion in its upper and its lower surface, respectively, the flange portions being coaxially arranged with the circularly-curved wall portions of the pistons;
each of an upper and a lower rotor ring is radially outwardly disposed so as to encircle each of the upper and the lower flange portion of the rotor and each of the circularly-curved wall portions of the pistons; and
a pressure oil supplied to the interior of the rotor is introduced into the interior of the piston to cool both the rotor and the piston.
Preferably, the pressure oil supplied to the interior of the rotor is introduced into the interior of the piston to lubricate both the piston rings and the rotor ring.
In the piston engine of the present invention having the above construction: there is no fear that the piston is subjected to a considerable lateral pressure; a pair of the connecting rods are employed; both the crank pins and the crank shafts are downsized; and, any counter weight is not employed, which makes it possible to save the oil agitation power of the engine, and, therefore to considerably improve the engine in machine efficiency. Further, in the piston engine of the present invention having the above construction: any vibration and noise caused by unbalanced mass or inertia of the engine components and those caused by couples of forces of the engine components are removed, which makes it possible to drastically reduce the torsional vibrations of the crank shafts.
Further, in the piston engine of the present invention having the above construction, it is possible to reduce the reciprocating masses of the circularly-curved cylindrical pistons and like engine components up to less than a quarter of those of the conventional reciprocating pistons and like conventional engine components. Consequently, it is possible for the piston engine of the present invention to considerably improve its engine performance. Further, since the piston engine of the present invention is of a double-acting type, it is possible for the piston engine of the present invention to reduce in size to a third of the conventional piston engine, which makes it possible for the engine of the present invention to be compact and lightweight, and further low in manufacturing cost.
The above makes it possible for the piston engine of the present invention to reduce its materials required in manufacturing, and thereby considerably reducing the power consumption in its production plant. Further, as for the internal combustion engine of the present invention, it is possible to considerably reduce the fuel consumption of the engine, and, thereby considerably reducing the amount of CO2 emitted from the engine.